Pufendorf and Leibniz on duties of esteem in diplomatic relations

The striving for self-worth is recognized as a driving force in international relations; but if self-worth is understood as a function of status in a power hierarchy, this striving often is a source of anxiety and conflict over status. The quasi-international relations within the early modern German Empire have prompted seventeenth-century natural law theorists such as Samuel Pufendorf and Gottfried Wilhelm Leibniz to reflect about this problem. In his De statu imperii Germanici (1667), Pufendorf regards the power differences and dependencies between the Reichsstände to be an expression of the deficits of constitutional structure of the Empire-a structure that, in his view, causes internal division because it leads to distorted practices of esteem between the estates. Against Pufendorf, Leibniz argues De jure suprematus ac legationis (1671) that political actors such as the German princes who are not Electors could fulfill functions under the law of nations such as forming confederations and peace keeping. Incoherently, however, Leibniz excludes less powerful estates such as the Imperial cities and the Hanseatic cities from the ensuing duties of esteem. This shortcoming, in turn, is arguably remedied in Pufendorf's later considerations concerning duties of esteem in diplomatic relations.

Wolff on duties of esteem in the law of peoples

The role that the desire for self-worth plays in international relations has become a prominent topic in contemporary political theory. Contemporary accounts are based on the notion of national self-worth as a function of status; therefore, the desire for national self-worth is seen as a source of anxiety and conflict over status. By contrast, according to Christian Wolff, there exists a duty to take care that both one's own and other political communities deserve to be esteemed. In his view, this duty is grounded in the duty of self-perfection because the qualities for which communities deserve to be esteemed are those that promote the self-perfection of individuals. From this perspective, he argues that duties of esteem toward political communities should not be seen as an outcome of power relations but rather as an outcome of the fulfillment of functions of the law of peoples. Wolff's line of argument draws attention to the possibility that anger over a violation of the desire for honor could be mistaken for an expression of specific culture-specific sensitivities, while what really may be expressed is a diverging interpretation of the implications of dependence in international relations.

Streptococci as the new dominant aetiological factors of mastitis in dairy cows in north-eastern Poland: analysis of the results obtained in 2013-2019

The objective of our study was to evaluate prevalence of selected bacterial and fungal pathogens of mastitis in dairy cattle in north-eastern Poland. Our study was conducted from 2013 to 2019 in 1,665 clinically and sub-clinically infected quarter milk samples (2013, n = 368; 2014, n = 350; 2015, n = 290; 2016, n = 170; 2017, n = 173; 2018, n = 224; and 2019, n = 90). The isolation and identification of the pathogens were performed in keeping with generally accepted microbiological procedures. In 2013, mastitis was most commonly caused by Staphylococcus aureus (24%), Streptococcus spp. (22%), Streptococcus agalactiae (12%) and coagulase-negative staphylococci (11%). In 2014, the most common pathogens were Streptococcus spp. (25%), Staphylococcus aureus (18%) and coagulase-negative staphylococci (10%); in 2015, 2016, 2017, 2018 and 2019, Streptococcus spp. (from 39–49%) were the most frequent strains isolated from the quarter milk samples. Other pathogens were isolated occasionally (below 15% in all years). In conclusion, the role of environmental bacteria has been gradually increasing in the Warmia Province. The importance of infectious pathogens has been decreasing, indicating the efficacy of the applied preventive programmes and a need for the development of new programmes targeting environmental pathogens.

Optimizing the Handling of Invasive Fungal Sinusitis Surgical Specimens

Introduction/Objective

Invasive fungal sinusitis (IFS) is an aggressive disease characterized by invasion of fungal hyphae into tissue/neurovascular bundles. This project assessed the handling of IFS specimens and implemented protocols to improve turnaround time (TAT).

Methods

A retrospective review of cases accessioned with a clinical concern for IFS from 2014-2019 was performed. TAT for each step in the specimen processing was recorded. A flowchart was created using stakeholder interviews and a revised protocol was developed after assessing critical needs. Assessment of interventions was performed following implementation of the new protocol. The protocol will be evaluated by prospective direct case-by-case feedback and after a 6-month interval (projected August/2020). At 6-months, goals are a 24 hours median time between frozen section and sign-out and elimination of outliers (greater than 2 working days).

Results

We identified 53 specimens from 32 patients in the pre-intervention period (36 cases positive for IFS). Median time from frozen section to final sign-out was 28 (5-312) hours. Four areas for improvements were identified:

(1) triaging specimens to different protocols according to arrival time, (2) optimized triaging for available histology processors, (3) standardized GMS ordering, and (4) standardized case delivery/communication with sign-out staff. Interventions include: protocol for processing specimens based on time of day, new histology protocols to expedite GMS performance, an email group for rapid communication with staff pathologists and histology, and a worksheet/checklist to track each case. After implementation of the protocol, 8 cases from 7 patients were received. Median time from frozen section to final sign-out was reduced to 20 (2 – 50) hours.

Conclusion

The protocol for handling IFS specimens became live on 2/1/2020. It has reduced TAT of suspected IFS cases, from a median of 28 hours to 20 hours. The longest interval to sign-out went from312 hours to 50 hours.

Helvétius's challenge: Moral luck, political constitutions, and the economy of esteem

This article explores a historical challenge for contemporary accounts of the role that the desire of being esteemed can play in exercising social control. According to Geoffrey Brennan and Philip Pettit, the economy of esteem normally has two aspects: it is supportive of virtuous action and it occurs spontaneously. The analysis of esteem presented by the 18th-century materialist Claude-Adrien Helvétius challenges the intuition that these two aspects go together unproblematically. This is so because, in Helvétius's view, the desire for esteem is always triggered by sensible interest. In the frequent situations where sensible interest diverges from the demands of virtue, the economy of esteem thus can be spontaneous but will not be supportive of virtue. Helvétius allows for cases of moral luck where sensible interest coincides with the demands of virtue but regards these cases as rare occurrences. This is why he believes that a functioning economy of esteem crucially depends on political constitutions-in which case the economy of esteem can be supportive of virtue but will not be spontaneous.

Assessment of individual tumor buds using keratin immunohistochemistry: moderate interobserver agreement suggests a role for machine learning

Tumor budding is a promising and cost-effective biomarker with strong prognostic value in colorectal cancer. However, challenges related to interobserver variability persist. Such variability may be reduced by immunohistochemistry and computer-aided tumor bud selection. Development of computer algorithms for this purpose requires unequivocal examples of individual tumor buds. As such, we undertook a large-scale, international, and digital observer study on individual tumor bud assessment. From a pool of 46 colorectal cancer cases with tumor budding, 3000 tumor bud candidates were selected, largely based on digital image analysis algorithms. For each candidate bud, an image patch (size 256 × 256 µm) was extracted from a pan cytokeratin-stained whole-slide image. Members of an International Tumor Budding Consortium (n = 7) were asked to categorize each candidate as either (1) tumor bud, (2) poorly differentiated cluster, or (3) neither, based on current definitions. Agreement was assessed with Cohen's and Fleiss Kappa statistics. Fleiss Kappa showed moderate overall agreement between observers (0.42 and 0.51), while Cohen's Kappas ranged from 0.25 to 0.63. Complete agreement by all seven observers was present for only 34% of the 3000 tumor bud candidates, while 59% of the candidates were agreed on by at least five of the seven observers. Despite reports of moderate-to-substantial agreement with respect to tumor budding grade, agreement with respect to individual pan cytokeratin-stained tumor buds is moderate at most. A machine learning approach may prove especially useful for a more robust assessment of individual tumor buds.

Potential clinical scenarios of tumour budding in colorectal cancer

Tumour budding, defined as single tumour cells or clusters of 4 tumour cells or less detached from the main tumour body, is a wellestablished indicator of aggressive tumour biology in colorectal cancer. As a marker of tumour dissemination, evidence points towards tumour budding as a morphological correlate of epithelialmesenchymal type changes in the tumour microenvironment. Despite many studies in the literature going back decades, tumour budding has not been systematically integrated in colorectal cancer reporting protocols. The recently published proceedings of the International Tumour Budding Consensus Conference (ITBCC) have sparked the systematic implementation of tumour budding in routine reporting of colorectal cancer. Tumour budding may be particularly relevant to patient management in endoscopically resected pT1 colorectal cancer, stage II tumour and pre-operative biopsies. The present review focuses mainly on these three potential clinical scenarios with the aim to provide a concise and updated overview on tumour budding in CRC.

Instrumental causes and the natural origin of souls in Antonio Ponce Santacruz's theory of animal generation

This article studies the theory of animal seeds as purely material entities in the early seventeenth-century medical writings of Antonio Ponce Santacruz, royal physician to the Spanish king Philipp IV. Santacruz adopts the theory of the eduction of substantial forms from the potentiality of matter, according to which new kinds of causal powers can arise out of material composites of a certain complexity. Santacruz stands out among the late Aristotelian defenders of eduction theory because he applies the concept of an instrument of direction developed by the medieval Avicenna commentator Gentile da Foligno and gives a novel turn to this concept by interpreting animal seeds as separate instruments. The article situates Santacruz's theory in the context of early modern debates about the concept of the eduction of forms, as well as in the context of early modern debates about the concept of separate instruments. Particular attention is paid to Santacruz's responses to the biological views of Julius Caesar Scaliger and Thomas Feyens. Santacruz's response to Scaliger turns out to be central for his explication of the eduction relation, and Santacruz's response to Feyens turns out to be central for his explication of the nature of instrumental causation.

[Management of chronic pain using extended release tilidine : Quality of life and implication of comedication on tilidine metabolism]

BACKGROUND AND OBJECTIVES

The synthetic opioid tilidine is often used in chronic pain treatment. However, the activation via metabolism in patients with concomitant medication and reduced liver or kidney function is not thoroughly investigated. We therefore studied pain treatment efficacy, health-related quality of live and the metabolism of tilidine in patients with chronic pain.

METHODS AND MATERIALS

In all, 48 patients, who were on a stable dose of oral prolonged release tilidine for at least 7 days, were included in this observational multicenter study. Liver and kidney function were assessed in routine blood samples, concentrations of tilidine, nortilidine and bisnortilidine were determined using a validated LC/MS/MS method. Comedication was registered and patients experience with regard to quality of life, pain, gastrointestinal symptoms and adverse events was assessed in standardised questionnaires.

RESULTS

On average a daily dose of 180 mg tilidine was taken. Dose normalized plasma concentrations of the active metabolite nortilidine ranged between 1.6 ng/ml and 76.5 ng/ml (mean 29.2 ± 25.1 ng/ml). Ratios between tilidine and nortilidine were on average 0.28 (median = 0.13, standard deviation = 0.67). Patients were on 1 to 14 different concomitant medications. About 66% of the patients had sufficient pain treatment. Almost no opioid-induced constipation was observed. Only few patients had decreased kidney or liver function which did not result in elevated nortilidine concentrations.

CONCLUSION

Pain treatment using tilidine resulted in variable nortilidine concentrations which are obviously not strongly influenced by comedication or reduced liver or kidney function. Only a few side effects were observed with almost no opioid-induced constipation.

Value, Justice, and Presumption in the Late Scholastic Controversy over Price Regulation

In the sixteenth and early seventeenth centuries, theories of price regulation were developed in order to analyze the demands of justice in situations where markets cease to function-be it through natural conditions, wars, or artificially induced shortages in supply. This article investigates the relevance of the methodological notion of presumption for the legally binding power of laws concerning price regulation. In particular, the relation between presumptions (assumptions that are taken to be true unless and until proven false), the cost-and-labor theory of value, and the question of the morally binding power of laws concerning legal prices are explored.

A new approach to distance measurements between two spin labels in the >10 nm range

ESR spectroscopy can be efficiently used to acquire the distance between two spin labels placed on a macromolecule by measuring their mutual dipolar interaction frequency, as long as the distance is not greater than ∼10 nm. Any hope to significantly increase this figure is hampered by the fact that all available spin labels have a phase memory time (T_m), restricted to the microseconds range, which provides a limited window during which the dipolar interaction frequency can be measured. Thus, due to the inverse cubic dependence of the dipolar frequency over the labels' separation distance, evaluating much larger distances, e.g. 20 nm, would require to have a T_m that is ∼200 microsecond, clearly beyond any hope. Here we propose a new approach to greatly enhancing the maximum measured distance available by relying on another type of dipole interaction-mediated mechanism called spin diffusion. This mechanism operates and can be evaluated during the spin lattice relaxation time, T₁ (commonly in the milliseconds range), rather than only during T_m. Up until recently, the observation of spin diffusion in solid electron spin systems was considered experimentally impractical. However, recent developments have enabled its direct measurement by means of high sensitivity pulsed ESR that employs intense short magnetic field gradients, thus opening the door to the subsequent utilization of these capabilities. The manuscript presents the subject of spin diffusion, the ways it can be directly measured, and a theoretical discussion on how intramolecular spin-pair distance, even in the range of 20-30 nm, could be accurately extracted from spin diffusion measurements.

O6-methylguanine-DNA methyltransferase activity is associated with response to alkylating agent therapy and with MGMT promoter methylation in glioblastoma and anaplastic glioma

Background

CpG methylation in the O⁶-methylguanine-DNA methyltransferase (MGMT) promoter is associated with better outcome following alkylating agent chemotherapy in glioblastoma (GBM) and anaplastic glioma (AG). To what extent improved response reflects low or absent MGMT activity in glioma tissue has not been unequivocally assessed. This information is central to developing anti-resistance therapies.

Methods

We examined the relationship of MGMT activity in 91 GBMs and 84 AGs with progression-free survival (PFS) following alkylator therapy and with promoter methylation status determined by methylation-specific PCR (MSP).

Results

Cox regression analysis revealed that GBMs with high activity had a significantly greater risk for progression in dichotomous (P ≤ 0.001) and continuous (P ≤ 0.003) models, an association observed for different alkylator regimens, including concurrent chemo-radiation with temozolomide. Analysis of MGMT promoter methylation status in 47 of the GBMs revealed that methylated tumors had significantly lower activity (P ≤ 0.005) and longer PFS (P ≤ 0.036) compared to unmethylated tumors, despite overlapping activities. PFS was also significantly greater in methylated vs. unmethylated GBMs with comparable activity (P ≤ 0.005), and among unmethylated tumors with less than median activity (P ≤ 0.026), suggesting that mechanisms in addition to MGMT promote alkylator resistance. Similar associations of MGMT activity with PFS and promoter methylation status were observed for AGs.

Conclusions

Our results provide strong support for the hypotheses that MGMT activity promotes alkylator resistance and reflects promoter methylation status in malignant gliomas.

General significance

MGMT activity is an attractive target for anti-resistance therapy regardless of methylation status.

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Largest study to date of association of MGMT activity with treatment response.

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MGMT activity is inversely associated with alkylator response in malignant gliomas.

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Mean activity is significantly lower in MGMT promoter-methylated tumors.

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Better response in methylated tumors is unlikely due to lower MGMT activity alone.

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Supports the use of MGMT inhibitors to improve responsiveness to alkylator therapy.

Nicolaus Taurellus on forms and elements

This article examines the conception of elements in the natural philosophy of Nicolaus Taurellus (1547-1606) and explores the theological motivation that stands behind this conception. By some of his early modern readers, Taurellus may have been understood as a proponent of material atoms. By contrast, I argue that considerations concerning the substantiality of the ultimate constituents of composites led Taurellus to an immaterialist ontology, according to which elements are immaterial forms that possess active and passive potencies as well as motion and extension. In Taurellus's view, immaterialism about elements provides support for the theological doctrine of creation ex nihilo. As he argues, the ontology of immaterial forms helps to explicate a sense in which creatures are substances, not accidents of the divine substance. In particular, he maintains that immaterial forms stand in suitable relations of ontological dependence to God: creation dependence (since forms would not exist without the divine act of creation), but neither subsistence dependence (since forms continue to exist without continued divine agency) nor activity dependence (since forms are active without requiring divine concurrence).

Estimation of spin-echo relaxation time

In spin-echo-based EPR oximetry, traditional methods to estimate the T2 relaxation time, which encodes the oxygen concentration of the sample, include fitting an exponential to the peaks or the integrated areas of multiple noisy echoes. These methods are suboptimal and result in a loss of estimation precision for a given acquisition time. Here, we present the maximum likelihood estimate (MLE) of T2 from spin-echo data. The MLE provides, for the data considered, approximately 3-fold time savings over echo-integration and more than 40-fold time savings over peak-picking. A one-dimensional line search results in simple computation of the MLE. It is observed that, perhaps counter-intuitively, prior knowledge of the lineshape does not yield additional reduction of estimation error variance at practical noise levels. The result also illuminates the near optimal performance of T2 estimation via principal components calculated by a singular value decomposition. The proposed method is illustrated by application to simulated and experimental EPR data.

Repair of 3-methyladenine and abasic sites by base excision repair mediates glioblastoma resistance to temozolomide

Alkylating agents have long played a central role in the adjuvant therapy of glioblastoma (GBM). More recently, inclusion of temozolomide (TMZ), an orally administered methylating agent with low systemic toxicity, during and after radiotherapy has markedly improved survival. Extensive in vitro and in vivo evidence has shown that TMZ-induced O(6)-methylguanine (O(6)-meG) mediates GBM cell killing. Moreover, low or absent expression of O(6)-methylguanine-DNA methyltransferase (MGMT), the sole human repair protein that removes O(6)-meG from DNA, is frequently associated with longer survival in GBMs treated with TMZ, promoting interest in developing inhibitors of MGMT to counter resistance. However, the clinical efficacy of TMZ is unlikely to be due solely to O(6)-meG, as the agent produces approximately a dozen additional DNA adducts, including cytotoxic N3-methyladenine (3-meA) and abasic sites. Repair of 3-meA and abasic sites, both of which are produced in greater abundance than O(6)-meG, is mediated by the base excision repair (BER) pathway, and occurs independently of removal of O(6)-meG. These observations indicate that BER activities are also potential targets for strategies to potentiate TMZ cytotoxicity. Here we review the evidence that 3-meA and abasic sites mediate killing of GBM cells. We also present in vitro and in vivo evidence that alkyladenine-DNA glycosylase, the sole repair activity that excises 3-meA from DNA, and Ape1, the major human abasic site endonuclease, mediate TMZ resistance in GBMs and represent potential anti-resistance targets.

Dielectric Resonator for Ka-Band Pulsed EPR Measurements at Cryogenic Temperatures: Probehead Construction and Applications

The construction and performance of a K_a-band pulsed electron paramagnetic resonance (EPR) cryogenic probehead that incorporates dielectric resonator (DR) is presented. We demonstrate that the use of DR allows one to optimize pulsed double electron-electron resonance (DEER) measurements utilizing large resonator bandwidth and large amplitude of the microwave field B₁ . In DEER measurements of Gd-based spin labels, use of this probe finally allows one to implement the potentials of Gd-based labels in distance measurements. Evidently, this DR is well suited to any applications requiring large B₁-fields and resonator bandwidths, such as electron spin echo envelope modulation spectroscopy of nuclei having low magnetic moments and strong hyperfine interactions and double quantum coherence dipolar spectroscopy as was recently demonstrated in the application of a similar probe based on an loop-gap resonator and reported by Forrer et al. (J Magn Reson 190:280, 2008).

Upgrading of a co-digestion plant by implementation of a hydrolysis stage

An existing co-digestion plant needed to be rehabilitated after a 20 year operational period. This was planned to be done in sequence by halving the digester volume for a period of 1.5 years. The aim of the present study was to improve the performance of the halved co-digestion capacity by implementing an upstream thermal hydrolysis reactor or an ultrasonic pre-treatment of the substrates. The results of the ultrasonic bench-scale batch experiments showed that an ultrasonic pre-treatment of the co-substrates 'municipal bio-waste suspension and excess activated sludge led to disintegration efficiencies of up to 51%. However, treating kitchen-waste and primary sludge in the same manner was not promising as the disintegration yields were rather low. The results of the hydrolysis bench-scale batch experiments showed that the optimal boundary conditions for the hydrolysis reactor were a hydrolysis temperature of about 42 °C at a retention time of 24 h. The results of the continuous two-stage experiments showed that it was possible to reduce the retention time in the second stage to about 24% and to increase the biogas yield to about 12.8 %, and the methane yield to about 28% as a result of the implementation of the hydrolysis reactor in the existing system. After the rehabilitation of the existing digesters it was possible to raise the daily substrate input to the two existing digesters from 312 to 495 m³ day(-1) with an upstream hydrolysis reactor volume of only 474 m³.

Apurinic/apyrimidinic endonuclease is inversely associated with response to radiotherapy in pediatric ependymoma

Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers radiation resistance in human cells. Here we examined the association between Ap endo activity and response to radiotherapy in pediatric ependymomas, tumors for which treatment options are limited and survival rates are only about 50%. We assayed Ap endo activity in 36 ependymomas and expression of Ape1/Ref-1, the predominant Ap endo activity in humans, in 44 tumors by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity or expression with progression-free survival or with overall survival. Activity varied 13-fold and was not associated with tumor or patient characteristics. In univariate models with Ap endo activity entered as a continuous variable, the hazard ratio for progression increased by a factor of 2.18 for every 0.01 unit increase in activity (p ≤ 0.003) in 24 grade II ependymomas. Risk for death increased by a factor of 1.89 (p ≤ 0.02) in the same population. The fraction of Ape1/Ref-1 immunopositive cells varied widely within individual tumors and was not associated with either progression-free or with overall survival. Suppressing Ap endo activity in pediatric ependymoma cells significantly increased radiation sensitivity, suggesting that the association of activity with radiation response reflected, at least in part, repair of radiation-induced DNA lesions. Our data indicate that Ap endo activity is predictive of outcome following radiotherapy, and suggest that Ape1/Ref-1 promotes radiation resistance in pediatric ependymomas. Our findings support the use of inhibitors of Ap endo activity to overcome resistance.

HIV-infected patients and treatment outcomes: an equivalence study of community-located, primary care-based HIV treatment vs. hospital-based specialty care in the Bronx, New York

The HIV-infected population in the USA is expanding as patients survive longer and new infections are identified. In many areas, particularly rural/medically underserved regions, there is a growing shortage of providers with sufficient HIV expertise. HIV services incorporated into community-based (CB), primary care settings may therefore improve the distribution and delivery of HIV treatment. Our objective was to describe/compare patients and treatment outcomes in two settings: a community-located, primary care-based HIV program, and a hospital-based (HB) specialty center. CB providers had on-site access to generalist HIV experts. The hospital center was staffed primarily by infectious disease physicians. This was a retrospective cohort study of 854 HIV-positive adults initiating care between 1/2005 and 12/2007 within an academic medical center network in the Bronx, NY. Treatment outcomes were virologic and immunologic response at 16-32 and 48 weeks, respectively, after combination antiretroviral therapy (cART) initiation. We found that HB subjects presented with a higher prevalence of AIDS (59% vs. 46%, p<0.01) and lower initial CD4 (385 vs. 437, p<0.05) than CB subjects. Among 178 community vs. 237 hospital subjects starting cART, 66% vs. 62% achieved virologic suppression (95% confidence interval (CI) difference -0.14-0.06) and 49% vs. 59% achieved immunologic success, defined as a 100 cell/mm³ increase in CD4 (95% CI difference 0.00-0.19). The multivariate-adjusted likelihoods of achieving viral suppression [OR=1.24 (95% CI 0.69-2.33)] and immunologic success [OR=0.76 (95% CI 0.47-1.21)] were not statistically significant for community vs. hospital subjects. Because this was an observational study, propensity scores were used to address potential selection bias when subjects presented to a particular setting. In conclusion, HIV-infected patients initiate care at CB clinics earlier and with less advanced HIV disease. Treatment outcomes are comparable to those at a HB specialty center, suggesting that HIV care can be delivered effectively in community settings.

Minimally cytotoxic doses of temozolomide produce radiosensitization in human glioblastoma cells regardless of MGMT expression

Concurrent treatment with the methylating agent temozolomide during radiotherapy has yielded the first significant improvement in the survival of adult glioblastomas (GBM) in the last three decades. However, improved survival is observed in a minority of patients, most frequently those whose tumors display CpG methylation of the O(6)-methylguanine (O(6)-meG)-DNA methyltransferase (MGMT) promoter, and adult GBMs remain invariably fatal. Some, although not all, preclinical studies have shown that temozolomide can increase radiosensitivity in GBM cells that lack MGMT, the sole activity in human cells that removes O(6)-meG from DNA. Here, we systematically examined the temozolomide dose dependence of radiation killing in established GBM cell lines that differ in ability to remove O(6)-meG or tolerate its lethality. Our results show that minimally cytotoxic doses of temozolomide can produce dose-dependent radiosensitization in MGMT-deficient cells, MGMT-proficient cells, and MGMT-deficient cells that lack mismatch repair, a process that renders cells tolerant of the lethality of O(6)-meG. In cells that either possess or lack MGMT activity, radiosensitization requires exposure to temozolomide before but not after radiation and is accompanied by formation of double-strand breaks within 45 minutes of radiation. Moreover, suppressing alkyladenine-DNA glycosylase, the only activity in human cells that excises 3-methyladenine from DNA, reduces the temozolomide dose dependence of radiosensitization, indicating that radiosensitization is mediated by 3-methyladenine as well as by O(6)-meG. These results provide novel information on which to base further mechanistic study of radiosensitization by temozolomide in human GBM cells and to develop strategies to improve the outcome of concurrent temozolomide radiotherapy.

Single-strand-preferring nuclease activity in wheat leaves is increased in senescence and is negatively photoregulated

Single-strand-preferring nucleases (EC 3.1.30.1) selectively cleave internucleotide bonds in single-stranded regions of predominantly duplex DNA and DNA.RNA hybrids and extensively degrade denatured DNA and RNA. The functions of single-strand-preferring nuclease in plants are unknown. We have monitored this nuclease activity in flag leaves of wheat (Triticum aestivum L. cv. Chinese Spring) undergoing natural senescence and in primary leaves of wheat seedlings undergoing dark-induced senescence. In falg leaves, nuclease activity remained at basal levels during the first 2 weeks after anthesis, while chlorophyll content increased to a maximum. Nuclease activity then rose in concert with a decline in chlorophyll, reaching a 16-fold elevation at 5 weeks post-anthesis, when 53% of the chlorophyll had been lost. When 8-day-old wheat seedlings were induced to senesce by placing them in darkness, nuclease activity rose without apparent lag, reaching a 13-fold elevation in 7 days, when 61% of the chlorophyll had been lost. The increase in nuclease activity was reversible upon reexposure of seedlings to light, a decline beginning without apparent lag. Reversibility was complete for plants that had been held in darkness for 5 days, with activity returning to the control level in 2 days. These senescence-related changes in nuclease activity, measured in conventional assays, were consistent with concomitant analysis by activity staining of sodium dodecyl sulfate/polyacrylamide gels. We conclude that an increase in single-strand-preferring nuclease activity is closely associated with wheat leaf senescence and that nuclease activity is subject to negative photoregulation.

Material souls and imagination in late Aristotelian embryology

This article explores some continuities between Late Aristotelian and Cartesian embryology. In particular, it argues that there is an interesting consilience between some accounts of the role of imagination in trait acquisition in Late Aristotelian and Cartesian embryology. Evidence for this thesis is presented using the extensive biological writings of the Padua-based philosopher and physician, Fortunio Liceti (1577-1657). Like the Cartesian physiologists, Liceti believed that animal souls are material beings and that acts of imagination result in material images that can be transmitted by means of medical spirits to the embryo. Moreover, while the Cartesian embryologists accepted such a view in a quite speculative way, one finds penetrating criticism of imagination theories of trait acquisition in the Late Aristotelian tradition. Evidence for this thesis is presented using the no less extensive biological writings of Liceti's contemporary, Emilio Parisano (1567-1643). In conclusion, the Late Aristotelian tradition itself provides the theoretical tools for excising immaterial formative forces from embryology and at the same time evinces a much more acute sense for the problems inherent in imagination theories of trait acquisition than the Cartesian tradition.

Julius Caesar Scaliger on plant generation and the question of species constancy

The sixteenth-century physician and philosopher Julius Caesar Scaliger combines the view that living beings are individuated by a single substantial form with the view that the constituents of the organic body retain their identity due to the continued existence and operation of their own substantial forms. This essay investigates the implications of Scaliger's account of subordinate and dominant substantial forms for the question of the constancy of biological species. According to Scaliger, biological mutability involves not only change on the ontological level of accidents but, in some cases, also change on the level of substantial forms. While he shares the received view that substantial forms themselves cannot undergo change, he maintains that relations of domination and subordination between substantial forms can undergo change. He uses his theory of how such changes can occur to explain cases of revertible plant degeneration. Moreover, in his view plants that belong to previously unknown biological species can emerge from changes in the relations between the many forms contained in plant seeds.

Perfusion culture promotes differentiation of oral keratinocytes in vitro

In order to reconstruct the mucosal lining of the oral cavity tissue engineered autologous mucosa grafts could be of great benefit. In conventional stagnant cultures cells often tend to dedifferentiate. Perfusion culture has been demonstrated to reestablish differentiation in various epithelial cell types. Thus, in secondary cultures of human oral keratinocytes from ten patients conventional stagnant culture versus perfusion culture technique was compared. Proliferation and state of differentiation as expressed morphologically and immunohistochemically were assessed. After 14 days oral keratinocytes in a perfusion culture system tend to be further differentiated. They build up a thicker epithelium (3.4+/-1.0 vs. 2.4+/-0.4 layers), form microridges, express cytokeratins 1, 2, 10, 11, 19 but not 13 in all cells and cytokeratins 5, 6 particularly in cells attached to the carrier membrane. In contrast, oral keratinocytes in stagnant culture do not form microridges and rather express cytokeratins 13, 14, and 19 in mattering amounts.

Mx proteins: GTPases involved in the interferon-induced antiviral state

Mx proteins have molecular masses between 70 and 80 kDa and their synthesis is tightly regulated by interferons in mammalian and non-mammalian vertebrates. Some Mx proteins function as intracellular mediators of the interferon-induced antiviral state. When suitable cDNA constructs were constitutively expressed in mouse 3T3 cells the mouse nuclear Mx1 protein conferred selective resistance to influenza virus. The human cytoplasmic MxA protein conferred resistance to influenza virus and vesicular stomatitis virus but not to other viruses. Mx1 blocks influenza virus mRNA synthesis within the nucleus of infected cells. Mx1 presumably interacts with the influenza virus polymerase subunit PB2, because overexpression of PB2 titrates out the Mx1 block. MxA does not inhibit mRNA synthesis of influenza virus; it inhibits a subsequent cytoplasmic viral multiplication step. A possible target is the transport of newly synthesized influenza virus polymerase proteins back to the nucleus. Inhibition by MxA of vesicular stomatitis virus, which replicates in the cytoplasm, is at the transcriptional level. Parts of the N-terminal halves of all known Mx proteins are highly conserved. They contain the typical GTP-binding motif and show significant homology to other members of a new family of GTPases that includes rat dynamin, Drosophila Shibire and the yeast proteins Vps1/Spo15 and Mgm1. Purified Mx1 and MxA proteins possess GTPase activity. The GTP/GDP conversion rates are about 40 per min, and Km values about 700 microM. Mx1 and MxA variants with mutations in the GTP-binding sequences that violate the consensus are unable to confer virus resistance in vivo or to hydrolyse GTP in vitro, suggesting that GTPase activity is necessary for antiviral activity of Mx proteins. We hypothesize that the antivirally active Mx proteins (directly or indirectly) bind to polymerase proteins of susceptible viruses, thereby abolishing normal viral polymerase function. Interaction of Mx with viral targets is probably a GTP-dependent process.

O6-methylguanine-DNA methyltransferase deficiency in developing brain: implications for brain tumorigenesis

The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) is a cardinal defense against the mutagenic and carcinogenic effects of alkylating agents. We have reported evidence that absence of detectable MGMT activity (MGMT(-) phenotype) in human brain is a predisposing factor for primary brain tumors that affects ca. 12% of individuals [J.R. Silber, A. Blank, M.S. Bobola, B.A. Mueller, D.D. Kolstoe, G.A. Ojemann, M.S. Berger, Lack of the DNA repair protein O(6)-methylguanine-DNA methyltransferase in histologically normal brain adjacent to primary brain tumors, Proc. Natl. Acad. Sci. U.S.A. 93 (1996) 6941-6946]. We report here that MGMT(-) phenotype in the brain of children and adults, and the apparent increase in risk of neurocarcinogenesis, may arise during gestation. We found that MGMT activity in 71 brain specimens at 6-19 weeks post-conception was positively correlated with gestational age (P<or=0.0015). Moreover, the proportion of specimens exhibiting MGMT(-) phenotype (MGMT content<0.42 fmol/10(6)cells or 255 molecules/cell) declined progressively from 76% (16/21) at 6-8 weeks to 13% (1/8) at 15-19 weeks. All liver specimens that accompanied MGMT(-) brain (15/15) had measurable MGMT activity, demonstrating that the phenotype was not systemic in these cases. In contrast to MGMT, apurinic endonuclease, DNA polymerase beta and lactate dehydrogenase activities were found in every brain extract assayed, and showed no significant relationship with gestational age. The observed gestational pattern has at least two implications for neurocarcinogenesis. (1) Early in development, brain tissue that has MGMT(-) phenotype and is rapidly proliferating may be especially vulnerable to alkylation-induced mutations, including mutations that lead to brain tumors. (2) Persistence of prenatal MGMT deficiency into postnatal life in a sub-population of individuals may increase brain tumor risk. Our findings provide possible mechanistic insight into epidemiologic data associating maternal alkylating agent exposure with brain tumor incidence.

Human glioma cell sensitivity to the sequence-specific alkylating agent methyl-lexitropsin

PURPOSE

Defining the cytotoxicity of individual adducts in DNA is necessary for mechanistic understanding of human brain tumor resistance to therapeutic alkylating agents and for design of DNA repair-related antiresistance strategies. Our purpose is to characterize the sensitivity of human glioma cells to methyl-lexitropsin (Me-lex), a sequence-specific alkylator that produces 3-methyladenine (3-meA) as the predominant (>90%) DNA lesion.

EXPERIMENTAL DESIGN

We quantitated the Me-lex cytotoxicity of 10 human glioma cell lines that differ in O(6)-methylguanine (O(6)-meG)-DNA methyltransferase (MGMT) and mismatch repair activity. We used antisense suppression of alkyladenine DNA glycosylase (AAG) and Ape1 to assess the contribution of 3-meA and abasic sites to lethality and measured abasic sites.

RESULTS

(a) The LD(10) for Me-lex varied widely among the cell lines. (b) MGMT-proficient lines were more resistant than MGMT-deficient lines, an unexpected finding because Me-lex produces very little O(6)-meG. (c) Suppression of AAG increased Me-lex killing and reduced abasic site content. (d) Suppression of Ape1 increased Me-lex killing and increased abasic site content. (e) Ablation of MGMT had no effect on Me-lex cytotoxicity.

CONCLUSIONS

(a) Me-lex is cytotoxic in human glioma cells and AAG promotes resistance, indicating that 3-meA is a lethal lesion in these cells. (b) Abasic sites resulting from 3-meA repair are cytotoxic and Ape1 promotes resistance to these derivative lesions. (c) A factor(s) associated with MGMT expression, other than repair of O(6)-meG, contributes to Me-lex resistance. (d) Me-lex may have clinical utility in the adjuvant therapy of gliomas. (e) AAG and Ape1 inhibitors may be useful in targeting alkylating agent resistance.

O6-methylguanine-DNA methyltransferase, O6-benzylguanine, and resistance to clinical alkylators in pediatric primary brain tumor cell lines

PURPOSE

Primary brain tumors are the leading cause of cancer death in children. Our purpose is (a) to assess the contribution of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) to the resistance of pediatric brain tumor cell lines to clinical alkylating agents and (b) to evaluate variables for maximal potentiation of cell killing by the MGMT inhibitor O6-benzylguanine, currently in clinical trials. Few such data for pediatric glioma lines, particularly those from low-grade tumors, are currently available.

EXPERIMENTAL DESIGN

We used clonogenic assays of proliferative survival to quantitate cytoxicity of the chloroethylating agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and the methylating agent temozolomide in 11 glioma and five medulloblastoma lines. Twelve lines are newly established and characterized here, nine of them from low-grade gliomas including pilocytic astrocytomas.

RESULTS

(a) MGMT is a major determinant of BCNU resistance and the predominant determinant of temozolomide resistance in both our glioma and medulloblastoma lines. On average, O(6)-benzylguanine reduced LD10 for BCNU and temozolomide, 2.6- and 26-fold, respectively, in 15 MGMT-expressing lines. (b) O6-Benzylguanine reduced DT (the threshold dose for killing) for BCNU and temozolomide, 3.3- and 138-fold, respectively. DT was decreased from levels higher than, to levels below, clinically achievable plasma doses for both alkylators. (c) Maximal potentiation by O6-benzylguanine required complete and prolonged suppression of MGMT.

CONCLUSIONS

Our results support the use of O6-benzylguanine to achieve full benefit of alkylating agents, particularly temozolomide, in the chemotherapy of pediatric brain tumors.

Apurinic endonuclease activity in adult gliomas and time to tumor progression after alkylating agent-based chemotherapy and after radiotherapy

PURPOSE

Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair enzyme that cleaves DNA at cytotoxic abasic sites caused by alkylating agents and radiation. We have observed that human glioma cells deficient in Ap endo activity are hypersensitive to clinically used alkylators (Silber et al., Clin Cancer Res 2002;8:3008.). Here we examine the association of glioma Ap endo activity with clinical response after alkylating agent-based chemotherapy or after radiotherapy.

EXPERIMENTAL DESIGN

Cox proportional hazards regression models were used to analyze the relationship of Ap endo activity with time to tumor progression (TTP).

RESULTS

In a univariate model with Ap endo activity entered as a continuous variable, the hazard ratio (HR) for progression after alkylator therapy in 30 grade III gliomas increased by a factor of 1.061 for every 0.01 increase in activity (P = 0.013). Adjusting for age, gender, extent of resection, and prior treatment strengthened slightly the association (HR = 1.094; P = 0.003). Similarly, the HR for progression after radiotherapy in 44 grade II and III tumors increased by a factor of 1.069 (P = 0.008). Adjusting for the aforementioned variables had little effect on the association. In contrast, we observed no association between activity and TTP in grade IV gliomas after either alkylator therapy in 34 tumors or radiotherapy in 26 tumors.

CONCLUSIONS

Our data suggest that Ap endo activity mediates resistance to alkylating agents and radiation and may be a useful predictor of progression after adjuvant therapy in a subset of gliomas.

The Werner syndrome protein confers resistance to the DNA lesions N3-methyladenine and O6-methylguanine: implications for WRN function

The Werner syndrome (WS) protein (WRN), a DNA helicase/exonuclease, is required for genomic stability and avoidance of cancer. Current evidence suggests that WRN is involved in the resolution of stalled and/or collapsed replication forks. This function is indicated, in part, by replication defects in WS cells and by hypersensitivity to agents causing major structural aberrations in DNA that block replication. We show here that antisense suppression of WRN in two human glioma cell lines reproduces hallmarks of the drug cytotoxicity profile of WS cells, namely, hypersensitivity to 4-nitroquinoline 1-oxide, camptothecin and hydroxyurea. We also show that antisense-treated cells are hypersensitive to methyl-lexitropsin, a site-specific alkylating agent that produces mainly N3-methyladenine, a cytotoxic and replication-blocking lesion. Antisense-treated cells are hypersensitive to O(6)-methylguanine adducts as well, but only when repair by O(6)-methylguanine-DNA methyltransferase is lacking. Our results illustrate the drug sensitivity caused by deficiency of WRN in a uniform genetic background. They extend the WRN DNA damage sensitivity spectrum to methyl base adducts that can result in blocked replication, and suggest that WRN may be required for resumption of processive replication when incomplete repair of DNA damage leaves blocking lesions at forks. The evidence that highly disparate lesions fall within the purview of WRN, and that abrogating DNA repair can reveal dependence on WRN, suggests that WRN may protect the genome from the lethal, mutagenic and carcinogenic effects of widely diverse DNA damage arising from endogenous processes and environmental agents.

The apurinic/apyrimidinic endonuclease activity of Ape1/Ref-1 contributes to human glioma cell resistance to alkylating agents and is elevated by oxidative stress

Alkylating agents are standard components of adjuvant chemotherapy for gliomas. We provide evidence here that Ape1/Ref-1, the major mammalian apurinic/apyrimidinic endonuclease (Ap endo), contributes to alkylating agent resistance in human glioma cells by incising DNA at abasic sites. We show that antisense oligonucleotides directed against Ape1/Ref-1 in SNB19, a human glioma cell line lacking O(6)-methylguanine-DNA-methyltransferase, mediate both reduction in Ape1/Ref-1 protein and Ap endo activity and concurrent reduction in resistance to methyl methanesulfonate and the clinical alkylators temozolomide and 1,3-(2-chloroethyl)-1-nitrosourea. An accompanying increase in the level of abasic sites indicates that the DNA repair activity of Ape1/Ref-1 contributes to resistance. Conversely, we also show that exposure of SNB19 cells to HOCl, a generator of reactive oxygen species (ROS), results in elevated Ape1/Ref-1 protein and Ap endo activity, enhanced alkylator resistance, and reduced levels of abasic sites. Given current evidence that heightened oxidative stress prevails within brain tumors, the finding that ROS increase resistance to clinical alkylators in glioma cells may have significance for the response of gliomas to alkylating agent-based chemotherapy. Our results may also be relevant to the design of therapeutic regimens using concurrent ionizing radiation (a generator of ROS) and alkylating agent-based chemotherapy.

Apurinic/apyrimidinic endonuclease activity is elevated in human adult gliomas

Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to ionizing radiation and alkylating agents in human cell lines. The major Ap endo in human cells is Ape1, an abundant multi-functional protein also known as Ref-1, Hap-1, and Apex. In this work, we assayed Ap endo activity in human adult gliomas to establish correlates with tumor characteristics, and in histologically normal brain adjacent to tumors to characterize changes in activity accompanying neurocarcinogenesis. To our knowledge, this is the first available analysis of Ap endo activity in human brain tumors. Mean activity in 84 gliomas of different diagnostic types and grades was 0.072 +/- 0.095 fmol abasic sites incised/cell/min, ranging approximately 550-fold from 0.00077 to 0.42. The mean for high-grade gliomas was 3.5-fold greater than for low-grade tumors (P < or = 4.0 x 10(-5)), a difference observed within all diagnostic types. Activity was correlated with the fraction of S-phase cells in diploid gliomas (P < or = 0.02), suggesting that proliferation could be a determinant of activity in these tumors. Activity was also correlated with S-phase fraction in the majority of aneuploid gliomas (P < or = 0.03). Moreover, within the aneuploid tumors, there was a significant relationship between activity and the fraction of aneuploid cells (P < or = 4.0 x 10(-4)). In the 58 cases analyzed, mean activity was 7.3-fold higher in gliomas than in adjacent histologically normal brain (0.070 +/- 0.10 versus 0.0096 +/- 0.012 fmol/cell/min; P < or = 3.0 x 10(-5)). Increased tumor activity was observed in 93% of tumor/normal pairs, indicating that elevation of Ap endo activity is characteristic of human gliomagenesis. The elevation was large within most pairs, being 13-fold on average and > or = 10-fold in 43% of cases. A concomitant increase in Ape1 protein was observed by Western blotting in the subset of tumor/normal pairs examined. A clinically important consequence of the increase in Ap endo activity that accompanies neurocarcinogenesis may be enhanced resistance to the radiotherapy and alkylating agent-based chemotherapy that are mainstays of adjuvant therapy for malignant gliomas.

Thermus aquaticus DNA polymerase I mutants with altered fidelity. Interacting mutations in the O-helix

Phe(667) in the conserved O-helix of Thermus aquaticus (Taq) DNA polymerase I (pol I) is known to be important for discrimination against dideoxy-NTPs. We show here that Phe(667) is also important for base selection fidelity. In a forward mutation assay at high polymerase concentration, wild type pol I catalyzed frequent A --> T and G --> T transversions and -1 frameshifts at nonreiterated sites involving loss of a purine immediately downstream of a pyrimidine. The mutants F667L and A661E,I665T,F667L exhibited large decreases in A --> T and G --> T transversions, and the triple mutant displayed reduction in the aforementioned -1 frameshifts as well. Kinetic analysis showed that the F667L and A661E,I665T,F667L polymerases discriminated against synthesis of A:A mispairs more effectively and catalyzed less extension of A:A mispairs than the wild type enzyme. These data indicate that Phe(667) functions in maintaining the error frequency and spectrum, and the catalytic efficiency, of wild type pol I. We also found that the strong general mutator activity conferred by the single A661E substitution was entirely suppressed in the A661E, I665T,F667L polymerase, exemplifying how interactions among O-helix residues can contribute to fidelity. We discuss the mutator and anti-mutator mutations in light of recently obtained three-dimensional structures of T. aquaticus pol I.

Quantitative estimation of attenuation in ultrasound video images: correlation with histology in diffuse liver disease

RATIONALE AND OBJECTIVES

To determine the relationship between the attenuation of backscatter intensity in B-scan images of the liver and diffuse liver disease in order to assess the usefulness of this method in providing quantitative objective characterization of diffuse liver diseases in general and in fatty liver in particular.

METHODS

Twenty-four healthy volunteers and 28 patients with elevated liver enzyme levels who underwent liver biopsy were included in this study. An automatic far-field slope (FFS) algorithm that estimates the decrease in amplitude of the backscattered echo as a function of beam depth was implemented on the noncompensated image that was acquired on a commercial phased-array ultrasound system fitted to a custom-built interface card. The images were processed at a work-station. All scans were acquired repeatedly, read, and graded blindly by experienced ultrasound radiologists. Histology obtained via needle biopsy was reviewed without knowledge of the ultrasound findings.

RESULTS

Analysis of the FFS data for fatty infiltration in all patient groups yielded a sensitivity of 67%, a specificity of 77%, a positive predictive value (PPV) of 77%, negative predictive value (NPV) of 67%, and an accuracy of 71%. The mean score of the ultrasound reviewers showed a sensitivity of 82%, a specificity of 66%, a PPV% of 68%, an NPV of 81%, and an accuracy of 72%. Normal FFS values (false-negative) were found in five patients with proved fatty infiltration. All of these patients had coexistent moderate to severe hepatic inflammation. However, FFS data in patients with uncomplicated (pure) fatty infiltration revealed a sensitivity of 100%, a specificity of 80%, a PPV of 89%, an NPV of 100%, and an accuracy of 92%. The best ultrasound score yielded a sensitivity of 100%, a specificity of 60%, a PPV of 80%, an NPV of 100%, and an accuracy of 85% in the same patients.

CONCLUSIONS

The data demonstrate an excellent sensitivity (100%) of the FFS values in patients with uncomplicated fatty infiltration. This was also the only group of patients in whom the FFS score was superior to the radiologists' best score. The FFS method can be used as a tool to follow up the response to a clinical or research treatment and to obtain standardization of pattern interpretation independently of the individual reader.